Germany’s competition watchdog has slammed Facebook for its ‘abusive’ data harvesting practices and added that the social networking behemoth is abusing its dominant position to “limitlessly” harvest user data from outside websites and apps.

The Federal Cartel Office (FCO) has released a preliminary assessment report wherein it has focused on Facebook’s use of third-party sites to track users’ browsing behaviour, often without their knowledge. The FCO said that they are of the view that Facebook is abusing this dominant position by keeping tabs on user activities without the users’ knowledge.

These third parties include Facebook-owned services such as WhatsApp and Instagram, but also sites and apps that are less obviously linked to Facebook, often through the “like” button at the bottom of a webpage.

The FCO said many users were unaware their movements on other sites were being shadowed by Facebook, and that it “can also not be assumed” that users consent to the data collection.

The data transmitted from third sources give Facebook a wealth of information about its users, from which the Silicon Valley titan benefits financially by offering targeted advertising on its website.

FCO president Andreas Mundt said the social network’s advertising space was “so valuable” precisely because it has “huge amounts of personalised data at its disposal”.

The anti-trust watchdog expects to finish its probe by mid-2018, some two years after it was launched. The FCO does not have the power to slap Facebook with a fine, but the company can be forced to alter or even cease some of its activities.

The German scrutiny marks another setback for Facebook in Europe at a time of heightened concerns over the tracking of personal data online.

On Monday, France’s data protection agency told WhatsApp it needed to obtain users’ permission to transfer some information to its parent company Facebook, and gave it a month to comply.